In the field of distribution, as the supply chain is now globalized and laborers are growing old, the manpower for handling loading/unloading operations is likely to be in short supply, while the distribution quantities are increasing. Therefore, in recent years, a transfer apparatus has come into wide use to transfer an article (also called an object, a package, or a load). In the transfer apparatus, it is required to stably handle the article that is difficult to secure by the conventional vacuum gripping device, such as an article with irregular surfaces, an article which is likely to be deformed, an article wrapped in paper, and an inclined article.
As the transfer apparatus, an orthogonal mechanism robot and an articulated arm robot are known. The orthogonal mechanism robot and the articulated arm robot typically tend to be increased in size. For example, in a case where the orthogonal mechanism robot grips the article from the upside, it is required to use a vertically long arm Therefore, in a case where there is a spatial limitation such that the height of a roof is low, the orthogonal mechanism robot cannot be installed.
In addition, even in an articulated arm robot, redundant joints tend to be required to avoid the existing machine in a case where the article is gripped from the upside. Furthermore, in a case where the articles are stacked in a rectangular shape in a box pallet provided with an intermediate shelf, the further redundant joints are required when the article near the intermediate shelf in the box pallet is taken out. Therefore, the robot is increased in size and in cost.